Lightning arrester

Abstract

A lightning arrester having an insulating cylinder which contains resistance elements made of zinc oxide which have a nonlinear voltage-current characteristic are stored. The insulating cylinder is fixed at least one sealing member having passages which connect the inside space of the insulating cylinder with the outside space thereof. These passages are covered with a material adapted to be softened or melted by a heat and are therefore closed in an air-tight manner. The arrester also includes an arc guide for producing arc type spark short-circuit externally of the insulating cylinder due to gas jetted from the passages upon an arc accident in the insulatng cylinder.

What is claimed is: 
     
       1. A lightning arrester comprising: an insulating cylinder having an inside, an outside and two ends;   resistance elements located within said cylinder and separated from said cylinder by a gap, said resistance elements being made of zinc oxide and having a nonlinear voltage-current characteristic;   sealing members fixed to both ends of said insulating cylinder for holding said resistance elements, at least one of said sealing members having therein a passage including an outlet for allowing gas to be jetted from the inside of said insulating cylinder;   a covering member made of an organic insulating material for covering an outlet of said passage and adapted to be softened or melted by heat, said covering member covering said insulating cylinder and being part of an outer peripheral surface of said insulating cylinder; and   an arc guide attached to each of said sealing members and adapted to produce an arc type spark short-circuit on the outside of said insulating cylinder when gas is jetted from said passage upon generation of an arc in said insulating cylinder.   
     
     
       2. A lightning arrester as claimed in claim 1, wherein said arc-guides are bowl shaped and having openings facing each other. 
     
     
       3. A lightning arrester as claimed in claim 1, wherein said sealing members and said arc guides have threaded parts for engaging each other. 
     
     
       4. A lightning arrester as claimed in claim 2, wherein said sealing members and said arc guides have threaded parts for engaging each other. 
     
     
       5. A lightning arrester as claimed in claim 1, wherein each of said passages consists of a passage which is axial with respect to a center axis of said sealing member and a passage which is radial with respect to said center axis of said sealing member. 
     
     
       6. A lightning arrester as claimed in claim 5 wherein said arc-guides are bowl-shaped and having openings which face each other. 
     
     
       7. A lightning arrester as claimed in claim 6, wherein said sealing members and said arc guides have thread parts which engage each other. 
     
     
       8. A lightning arrester as claimed in claim 1, wherein said covering member is made of a silicone rubber. 
     
     
       9. A lightning arrester as claimed in claim 1, wherein both of said sealing members have said passages therein.